A：15
B：33
C：51
D：63
①G→Q+NaCl ②Q+H2O→X+H2 ③Y+NaOH→G+Q+H2O ④Z+NaOH→Q+X+H2O
则G，Q，X，Y，Z这五种化合物中氯元素的化合价由低到高的顺序为（ ）
She's not strong enough ____________ walking up mountains.
下列对实验现象的描述或实验操作正确的是（ ）
Ricky had a bad headache yesterday, he had to stay at home.
